If you’re not seeded No. 1 or No. 2, history suggests you won’t reach the NBA Finals, much less win the title.

Of the past 20 champions, 18 have been seeded No. 1 or No. 2 in their respective conferences.

The two exceptions were the 2007 Spurs and 1995 Rockets, veteran teams that had won before. Every other champion since the 1988-89 season was seeded No. 1 or No. 2 (see chart).

San Antonio was assisted by No. 8 seed Golden State’s upset of Dallas two years ago. The Spurs regained home-court advantage in the Western Conference finals after eliminating Phoenix in the semifinals.

Being the No. 1 or No. 2 seed also is critical just to reach the Finals. The past two decades, 90 percent of the teams in the Finals (36 of 40) were seeded No. 1 or No. 2.

The Knicks, a No. 8 seed in 1999, were an aberration because of the lockout year. The other exception was the 1990-91 Lakers, a No. 3 seed that benefited from No. 2 seed San Antonio losing in the first round.

Which brings us to the current season.

Races for the No. 1 seeds essentially are over. The Lakers (West) and Cavaliers (East) are locks to nail down the top spots.

But as history shows, the race for the No. 2 seed could be significant.